I don't have that quest anymore, but you can get the quest in Sawtooth Cauldron around the north-east part of the map. I think. --- GT: Optik4 You don't need to be a better shot, you just need to shoot more bullets!
As far as I know, it's unreachable after you finish the quest. All doors are locked and red. I already beat the normal playthrough and I'm nowhere near the Caverns on my TVH playthrough, --- Advance upon my position, brethren! Gamertag: A Few Moose
fast travel to caustic caverns go to your right, right after you leave that building. A door is open in there.
Going to the right leads me to deathy pools of death and death. Going left, there's a door, yes. But that's not where I need to go. This is a quest specific location --- Advance upon my position, brethren! Gamertag: A Few Moose